The project also allows pupils from Grade 10 to 12 to download the books free - and provides videos and presentations that they can source via the internet or on their cellphones.

The textbooks are written by an army of volunteers, many of whom are PhDs , and are provided free of charge to schools.

The initiative - called Siyavula - is the brainchild of Mark Horner, 35.

Horner's project is a labour of love that began in 2002 when he ran a project with graduate students at the University of Cape Town. Called the Free High School Science Textbook, it ran until early 2007 when he got a fellowship at the Shuttleworth Foundation.

He then started Siyavula - which means "we are opening" in Nguni.

Now it costs government only R40 to print and distribute one of these textbooks, whereas previously the Department of Basic Education had to fork out R150 a book. Schools can also download the books and print them at their own cost.

Allan Subban, the department's director of Enhancement of Programmes and Evaluation of School Performances, said 2.4-million books were printed this year at a cost of R73-million .

The ground-breaking project used a legal framework that allows content to be licensed and used free of charge.

Horner said: "Education is the foundation on which we solve all problems. Education makes the world a better place to live in. It makes it a better place for everyone. It's very satisfying."

And, he said, the reaction from pupils has been overwhelming.

"If you read the comments on our Facebook page, you know it's all worthwhile from the comments from the kids themselves."

The textbooks are supplemented by videos and presentations which are available on the internet and for cellphones. The books can also be downloaded in PDF format.

Siyavula works closely with the Department of Basic Education to make sure the books are in line with the school curriculum.

Subban said the project "ensures that every pupil has a textbook in their hands".

"Textbooks of this nature are not expensive. We can also specify the kind of paper that's used, the quality of printing, and the kinds of binding, all of which affect the durability of a textbook," he said. "An average book of this nature costs R150. If you do the maths, obviously it's quite significant," he added.

Caren Ehlers, the head of department for maths at Vredenburg High School in the Western Cape, which uses the books, said: "The pupils work out of those books. It's really helping them a lot ... especially now when it's exam time and test time."

Harry Mnisi, principal of Mahlale High in Bushbuckridge, Mpumalanga, told the Sunday Times: "They [the books] are good. The learners are responding well."

Max Kaizen, the country lead for Creative Commons in South Africa, said Siyavula is part of a global movement to provide free education resources, known as Open Education. Institutions include MIT, Yale, Harvard, Oxford and the University of Cape Town.

Creative Commons is a non-profit organisation offering free legal licenses, consistent with the rules of copyright, that make it easier for people to share and build on the work of others.

"Siyavula is one of many outstanding projects that contribute teaching-wares to the wealth of our global educational commons," she said.

The US Secretary of Education, Arne Duncan, said that the Obama administration was "investing up to $2-billion ... to create state-of-the-art courses" using Open Education resources.

The books can be downloaded from Everythingscience.co.za and Everythingmaths.co.za